When dealing with cash donations there is an overlap between recording a bidder donation or a donor donation. There is no single right answer to which way it should be recorded, but a couple of guidelines help.

In general, a donation should be considered a donor donation if:

it is made and paid for prior to the event and is in lieu of donating an item for auction available toward the event.

the donor isn't going to be a bidder participant at the event.

you don't need to track the commitment to the donation separately from the payment.

with a donor donation, you simply record the donation when it is actually made.

with a bidder donation, you need to record both the donation and the payment.

It is common to want to sell sponsorships online alongside event tickets.

In order to do this you need to set up sponsorships as 'for sale' items and when a someone buys one online they will be tracked as a bidder and the item shows up on their bidder statement.

If you also want the donor acknowledged as a donor/sponsor on the web site then you would need to manually record a donor donation for them and check the sponsorship and in-kind options. By checking the in-kind option for these you prevent the system double counting the income, since the amount is already tracked as a bidder purchase.